This invention relates in general to the field of exhaust hoods and more particularly to a method and system for exhausting heat and vapors generated by pizza ovens.
The pizza ovens which are used in the food industry to cook pizzas generate considerable heat and also create grease laden air, smoke and vapors, all of which must be exhausted from the building. Typically, an exhaust hood of some kind is installed above the pizza oven and equipped with an exhaust fan which operates to exhaust the heat and vapors that enter it. Conventional pizza oven hoods effect a front to back flow of air which is somewhat inefficient because the rising heat and vapor must be abruptly churned through a right angle in the hood. Furthermore, the flow pattern can be disrupted by local areas of turbulence which can reduce the efficiency and effectiveness of the exhaust system.
The volume of air that is exhausted from within the building by the exhaust hood must be made up by other air handling equipment. Thus, in the winter, the furnace must be operated to heat the air which serves as make up air to replace the volume that is exhausted by the pizza oven hood. Conversely, the air which is drawn into the building to replace the air that is exhausted in the summertime must be cooled by the air conditioning system of the building. In both cases, there are added energy demands on the air handling equipment, and these lead to significant additional costs.
The present invention is directed to an improved exhaust hood system which overcomes many of the aforementioned problems associated with conventional pizza oven hoods. In accordance with the invention, a specially constructed pizza oven hood has a central intake plenum which extends above the pizza oven from front to back. Outside air is forced into the intake plenum by an intake fan. A baffle in the intake plenum deflects the incoming air toward and along the plenum walls toward a restricted throat portion of the plenum. A special air deflector in the throat area of the plenum forms two slots through which the air passes in opposite directions toward the opposite sides of the hood.
It is an important feature of the invention that the intake system provides two oppositely flowing air streams which travel at a relatively high velocity from the center of the hood toward the opposite sides. This high velocity air flow creates a suction effect which induces heat, smoke, vapors and grease laden air into the hood for entrainment with the air streams. The hood includes exhaust plenums at its opposite sides and an exhaust fan which draws air from the hood through inclined grease filters and into the exhaust plenums and then out of the building through suitable exhaust ducts.
This construction provides an efficient exhaust system which operates by induction to draw heat and vapors from the oven into the hood where entrainment with the incoming air carries the heat and vapors out through the exhaust side of the system. The intake system creates this induction effect as a result of the high velocity air flow from the slots, and the hood is arranged so that the air flow pattern is symmetrical and covers the entire area of the pizza oven, thus avoiding areas of turbulence and other flow disruptions. At the same time, the volume of the make up air that enters through the intake system is carefully controlled in order to avoid unduly adding to the load of the existing air handling equipment of the building.